Minority populations may experience poorer health status than majority populations because they because they receive proven-effective health care services less often. These underuse problems may have different causes in minority compared with majority populations. Interventions to increase the delivery of effective health care services are likely to be most effective if they are tailored to address the specific causes of the underuse problems they seek to remedy. In this program, we propose a series of 4 coordinated projects that will measure the underuse of selected, proven-effective medical and surgical interventions in the large and ethnically-diverse communities of East and Central Harlem in New York City. We will assess the underlying causes of these underuse problems. We will develop, implement, and evaluate interventions to eliminated underuse by targeted underlying causes. Specifically, in a sample of East and Central Harlem Blacks and Hispanics, we will assess the magnitude of poor control of hypertension and assess patient, physician, and system reasons for these failures. We will use a randomized controlled trial (RCT) design to test the effectiveness of a nurse case management intervention to improve hypert4ension control among East and Central Harlem Blacks and Hispanics. In a sample of patients discharged alive from 4 East and Central Harlem hospitals with stroke, we will assess the magnitude and reasons for underuse of 4 proven-effective treatments for prevention of recurrent stroke. We will use an RCT design to evaluate the effectiveness of a nurse-managed computerized physician reminder system coupled with improved patient education on decreasing underuse. We will assess the effectiveness of a computerized reminder system with feedback on improving underuse of effective local and systemic adjuvant treatments for breast cancer. Finally, we will assess the magnitude of underuse of 3 proven-effective treatments for managing premature births and measure differences in underuse among Whites, Blacks, and Hispanics. Using qualitative methods, we will also explore reasons for underuse of these treatments. This program will be implemented as an integrated whole, supported by administrative, data management, and implementation and dissemination cores. These cores will provide support for common research methods and needs across projects and assure that projects are coordinated and benefit from each other's experiences. Dissemination of results will be accomplished through our close partnership with local community, state and national organizations.